sin.hpp

浮点数基本运算 浮点数的基本运算主要有四则运算、符号处理、大小比较

// Sin implementation -*- C++ -*-

// Copyright (C) 2005 Ben T. Bear
//
// This file is part of the BTB's Template<Integer> Library.  This
// library is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this library; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
// MA 02111-1307, USA.

// As a special exception, you may use this file as part of a free
// software library without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to
// produce an executable, this file does not by itself cause the
// resulting executable to be covered by the GNU General Public
// License.  This exception does not however invalidate any other
// reasons why the executable file might be covered by the GNU General
// Public License.

#ifndef __bt2il_sin_hpp
#define __bt2il_sin_hpp

#include "pi.hpp"

namespace btil
{
  namespace fn
  {
    template <typename x>
    struct sin;


    template <typename x>
    struct __sin;

    template <typename x>
    struct sin
    {
      static const double __t = (int)(x::f_val / (pi::f_val * 2.0));
      static const double __x = x::f_val - __t * 2.0 * pi::f_val;
      static const double __s = ((__x <= pi::f_val)
				 ? __x : __x - 2.0 * pi::f_val);
      
      struct xx
      {
	static const double f_val = __s;
      };

      typedef typename __sin<xx>::value value;
    };


    template <int n, typename x>
    struct __sin_item;

    template <typename x>
    struct __sin
    {
      typedef typename __sin_item<35, x>::sin_n value;
    };

    template <typename x>
    struct __sin_item<0, x>
    {
      struct item
      {
	static const double f_val = x::f_val;
      };

      typedef item sin_n;
    };

    template <int n, typename x>
    struct __sin_item
    {
      struct item
      {
	static const double f_val = (-__sin_item<n-1, x>::item::f_val
				     * x::f_val * x::f_val 
				     / (n*2) / (n*2+1));
      };

      struct sin_n
      {
	static const double f_val = (__sin_item<n-1, x>::sin_n::f_val
				     + item::f_val);
      };
    };
  }
}

#endif